For many years disc braking systems have been employed in a variety of automotive vehicles. Over the years a number of improvements have been made in these systems such as the utilization of composite friction materials, computer controlled hydraulic actuating systems, and the like. Despite the host of improvements made in disc braking systems, inherent problems associated therewith still exist. One such problem has been the high frequency noise which is produced, in part, by movement between the brake pad and the hydraulic actuating piston, and, in part, by rattling of the brake pad within the caliper housing while the vehicle is in motion and the brake system is at rest. Present attempts at solving the noise problem have been unsatisfactory because they involve a number of parts which are difficult to install and which increase the costs to manufacture and maintain the disc brake systems, without effectively eliminating noise.
Common attempts to reduce noise due to rattling of the pad within the caliper housing involve the use of anti-rattle clips or shoe support springs which are typically clipped, staked or riveted to the pad backing plate. These clips frictionally engage the interior wall of the piston in an attempt to stabilize movement of the pad when the brakes are at rest and the vehicle is in motion. The primary drawbacks to such efforts are that assembly is difficult and success in reducing noise depends heavily on proper installation, including positive contact between the clip and the piston. Further, present clips typically only contact the piston at a single point, thereby allowing some movement of the pad relative to the piston.
Common attempts at reducing noise due to movement of the pad relative to the piston when the braking system is applied typically involve the use of a gasket or shim interposed between the pad backing plate and the piston. This shim is intended to act as an insulator between the pad and piston, thereby interrupting and dampening any vibration between the two components. The primary drawback of such attempts is that the shim must be applied to the pad in a separate manufacturing step, such as by use of a suitable adhesive, thereby increasing manufacturing costs. If the shim is installed at the time the pads are installed on the vehicle, installation is further complicated and effective noise reduction, again, depends on proper installation.
Recently, automobile manufacturers along with brake system designers have sought to reduce the costs and space requirements of braking systems and to simplify installation and maintenance thereof without compromising quality or safety. The need persists, therefore, to reduce the number of components involved in brake systems, thereby reducing costs, inventory and space requirements. It is further desired to make installation and maintenance virtually "foolproof" so that positive, noise free operation may be safely and consistently accomplished.